Jupiter is the largest of the known planets in our solar system, and the nearest of the “outer” planets, which are typically gas giants (planets whose composition is chiefly gaseous).  Because of the gaseous makeup of Jupiter, it would have been the best candidate for a second star in our solar system.  According to astrophysicists, Jupiter only needs to be approximately eighty times its current mass in order for nuclear fusion to effectively ignite the planetary core.  In addition, Jupiter is known to radiate more energy than it actually receives from the sun, undoubtedly an indication that some massive energy-yielding reactions are taking place somewhere beneath the swirling Jovian atmosphere.

Perhaps the most well-known feature of Jupiter visible from Earth with an adequate telescope is the Great Red Spot.  It is a gigantic hurricane-like storm found in the convergence zone between two powerful opposing bands of jet-stream activity in Jupiter's upper atmosphere.  The discovery of Jovian meteorology is attributed to either Cassini or Robert Hooke in the 17th century.

Jupiter has as many as 16 natural satellites, the largest among these being Ganymede, Callisto, Io, and Europa.  Several of the smaller satellites may have once been asteroids which at some time in the past became ensnared by Jupiter's massive gravity.

The planetary symbol of Jupiter as seen above dates back to the days when alchemy was a popularly respected science.  Its form (besides being the ancient symbol for the lightning bolt, Jupiter's weapon of choice) symbolises the circular arc of spiritual potential lifting the cross of the material elements.  This symbolic context is also paralleled in the planetary symbol of Venus.

In astrology, Jupiter is attributed influence over that part of one's life concerning greatness, or “Fortune”; this influence is a higher resonance of that of the planet Venus.  As the antithesis of the Saturnian influence which represents change, Jupiter's influence may be interpreted as patience, fidelity, stability (or stagnancy, in the event of a negative aspect).

The zodiacal colour of Jupiter is violet, but the colour of its corresponding kabbalistic sefirah (divine emanation), Chesed (Mercy), is blue.  Tin (L:  stannum; Heb:  b'dihl) is the metal affiliated with Jupiter.

The day of the week corresponding to Jupiter is Thursday, whose Anglish name is derived from the Norse god Thor, god of thunder and lightning and of the storm.  In Romance languages, this day is assigned to Jupiter: